In order to be able to achieve the highest possible track density when using PMR (perpendicular magnetic recording), it is necessary to include side shields that reduce fringe effects and minimize side erasure. FIG. 1 is a plan view of the structure in question. Seen there are main body (yoke) 11 in which the write field will be induced by the activation of the field coils (not shown), side shields 12, and perpendicular write pole 13. Line 14 shows where the ABS (air bearing surface) will eventually be located, following the removal (by grinding and polishing) of the material below it.
It is important that the write pole be symmetrically located within the space between the side shields. If it is too close to one side or the other, one or more of the following problems may arise:
1) a reduction in overall process yield due to occasional shorting between the shield and the write pole
2) fringe effects at the pole edge farthest from shield
3) uneven side erasure.
A number of proposals have been put forward that use subtractive methods (such as RIE, IBE etc.) to etch an opening in a magnetic shield layer followed by standard ALD (atomic layer deposition), electroplating, and CMP methods to form the write pole inside said opening. However, in none of these approaches is the positioning of the write pole structure, between the side and trailing shields, accomplished through self-alignment, making the possibility of the occurrence of one or more of the problems listed above that much more likely.
These problems have been overcome through the development of the self-aligning method that we disclose below.
A routine search of the prior art was performed with the following references of interest being found:
U.S. Patent Applications 2006/0174474(Le) and 2006/0044682 (Le et al) teach forming self-aligned wrap-around side and trailing edge shields. In U.S. Patent Application 2006/0002019, Guthrie et al. show Rh as a CMP stop layer in forming a self-aligned trailing shield. U.S. Patent Application 2005/0259355 (Gao et al) teaches self-aligned formation of trailing shields using Rh as a stop layer.
In U.S. Pat. No. 7,002,775, Hsu et al. disclose side shields and trailing shields, preferably made of the same material. The method of formation is not disclosed. U.S. Pat. No. 7,070,698 (Le) shows side shields and a trailing shield formed in separate steps.
U.S. Pat. No. 7,068,453 (Terris et al.) describes side shields and trailing shield around the write pole while, in U.S. Pat. No. 7,031,121, Khera et al. show read element shields and a trailing shield. U.S. Patent Application 2005/0237665 (Guan et al.) shows a leading shield, trailing shield, and two side shields to overcome side fringing. No fabrication details are given.